Brock has played well since taking over for injured Brown at right cornerback during the Nov. 17 game against the Saints. He leads the 49ers with four interceptions; Brown has none. Brown returned to practice this week but is wearing a blue, non-contact jersey and appears at least a week away from being ready to play.

Perhaps more significant: The 49ers gave Brock a four-year, $16 million contract last month whereas Brown appears likely to become a free agent in March. The 49ers and Brown's representative have been trying to work out a deal since Brown forfeited a $2 million workout bonus in his current contract after training during the offseason in his native Texas not at team headquarters in Santa Clara. No deal has been struck.

The 49ers appear to be pondering a cornerback group of the future in which Brock, Chris Culliver and Eric Wright form the core.

MATTHEW BARROWS

Matt was born in Blacksburg, Va., and attended the University of Virginia. He graduated in 1995, went to Northwestern for a journalism degree a year later, and got his first job at a South Carolina daily in 1997. He joined The Bee as a Metro reporter in 1999 and started covering the 49ers in 2003. His favorite player of all time is Darrell Green.